checknameservlet.java

jsp+servlet经典的登录注册

package servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import dao.RegisterDAO;

public class CheckNameServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("gbk");
		response.setContentType("text/html;charset=gbk");
		PrintWriter out = response.getWriter();
		HttpSession session = request.getSession();
		
		/*
		String userName = (String)session.getAttribute("userName");
		RegisterDAO dao = new RegisterDAO();
		String sql = "select count(*) from register where userName=?";
		int n = dao.CheckName(sql, userName);
		*/
		
		String userName = request.getParameter("Name");
System.out.println(userName);
		RegisterDAO dao = new RegisterDAO();
		String sql = "select count(*) from register where userName=?";
		int n = dao.CheckName(sql, userName);
		session.setAttribute("Name", userName);
		
		if(n > 0){
			//用户名不能相同，提示
			out.write("<script type='text/javascript'>oNewWindow=open('../checkuserNameNotUse.jsp','','height=200 width=400');</script>");
		} else {
			//用户名可以使用
			out.write("<script type='text/javascript'>oNewWindow=open('../checkuserNameUse.jsp','','height=200 width=400');</script>");
		}
		//用重定向出现的问题
		//response.sendRedirect("../register.jsp");
		//不用重定向，用转发
		
		request.getRequestDispatcher("/register.jsp").include(request, response);
		
		out.flush();
		out.close();
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doGet(request, response);
	}

}